<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="./jq-3.6.0.js"></script>
</head>

<body>
    <div id="box">
        <div class="item"></div>
        <div class="item"></div>
        <div class="item"></div>
        <div class="item"></div>
    </div>
    <div class="pink">
        <div class="item"></div>
        <div class="item"></div>
        <div class="item"></div>
        <div class="item"></div>
    </div>
</body>
<script>
    //id选择器
    var box = $('#box');
    console.log(box);
    //全选选择器
    var all = $('*');
    console.log(all);
    //类选择器
    var items = $('.item');
    console.log(items);
    //并集选择器
    var boxAndPink = $('#box,.pink');
    console.log(boxAndPink);

    //交集选择器
    var boxItems = $('div.item');
    console.log(boxItems);
</script>

</html>